Heat activated self discharging fire extinguisher

ABSTRACT

An automatic discharge fire extinguisher adapted to release flame retardant material upon exposure to a predetermined temperature. The extinguisher incorporates a spring loaded piercing device which is released by action of an expansion tube and which breaks the seal on a pressurized vessel holding the flame retardant material.

United States Patent [1 1 Miley June 23, 1974 [54] HEAT ACTIVATED, SELF DISCHARGING 3,126,128 3/1964 Borsack et al 222/5 FIRE EXTINGUISHER 3,490,649 1/l970 Sheridan... i. 222/5 3,754,602 8/1973 Magdars 169/26 X Inventor: George E. Miley, 933 Alden Ln..

Buffalo Grove, 111. 60090 Filed: May 29, 1973 Appl. No.: 364,896

US. Cl 169/58, 169/60, 169/26,

Int. Cl. A62c 3/10 Primary Examiner-M. Henson Wood, J r.

Assistant Examiner-Michael Y. Mar

Attorney, Agent, or Firm-Hill, Gross, Simpson, Van Santen, Steadman, Chiara & Simpson ABSTRACT An automatic discharge fire extinguisher adapted to release flame retardant material upon exposure to a predetermined temperature. The extinguisher incorporates a spring loaded piercing device which is released by action of an expansion tube and which breaks the seal on a pressurized vessel holding the flame retardant material.

10 Claims, 5 Drawing Figures HEAT ACTIVATED, SELF DISCHARGING FIRE EXTINGUISI-IER BACKGROUND OF THE INVENTION While many different types of fire extinguishers have been developed, some of which aim at automatic discharge of flame retardant materials in response to increase in environmental temperatures, there are few satisfactory heat activated, self discharging fire extinguishers using pressurized cannisters of solid, liquid, or gaseous flame retardant materials. Apparently, it has been difficult to develop simple, reliable relatively inexpensive systems utilizing such cannisters.

BRIEF SUMMARY OF THE INVENTION There has now been discovered a heat activated, self discharging fire extinguisher which is adapted to release the contents of a pressurized cannister or the like charged with flame retardant material when the extinguisher is exposed to a predetermined set temperature. This extinguisher is relatively simple to fabricate and may be utilized for a number of different types of applications without major modification. This fire extinguisher is especially well adapted for use in areas where grease or oil, fires, or spontaneous combustion, might occur, such as fryer and grill areas of institutional kitchens, automotive garages, vehicles, oily waste disposal areas, and the like. The present extinguisher is in the nature of a semi-portable device requiring no extensive threaded pipe and/or sensor installation and is simply and easily bracketed in a position desired for use. Optionally, the extinguisher is adapted to be set for the temperature limits of the particular application environment.

Other and further objects, purposes, advantages, and the like will be apparent to those skilled in the art from a reading of the present specification taken with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a vertical, sectional view longitudinally taken through one embodiment of a fire extinguisher of this invention, with the piercing device in an open position;

FIG. 2 is a vertical sectional view transversely taken along the line IIII of FIG. 1;

FIG. 3 is a fragmentary vertical sectional view through the region of a safety pin in the embodiment of FIG. 1;

FIG. 4 is a fragmentary view similar to FIG. 1 but showing the piercing device in a closed position; and

FIG. 5 is a fragmentary vertical sectional view transversely taken through the expansion tube region of another embodiment of a fire extinguisher of this invention.

DETAILED DESCRIPTION Turning to the drawings, there is seen in FIGS. 1 and 2 a fire extinguisher of this invention, herein designated in its entirety by the numeral 10. Fire extinguisher utilizes a housing 11 conveniently formed of a cast metal, such as aluminum, or the like. The housing 11 is conveniently formed of two sections designated herein as section 11a and section 11b, respectively, which meet along a porting line 20. A conduit 12. with integrally formed perforated tabs 13, 14 and 15, is

mounted in watching slots of the housing 11 adjacent one wall 27 thereof between sections 110 and 11b. Conduit 12 is generally cylindrical in section and has a straight longitudinal axis 17.

The extinguisher It) incorporates a plunger assembly which is herein designated in its entirety by the numeral 18. The plunger assembly 18 incorporates a cylindrical, elongated, tube member 19, the forward portion of which is received in telescopic engagement within conduit 12. The forward end portion of tube member 19 terminates in a point 21. In the embodiment 10, the point 21 is formed by the crossover between two V- shaped members 22 and 23 which are interconnected together at their apex, are positioned apart with respect to their individual leg portions, and are each welded at their respective parts of opposed open ends to the forward edge region of the tube member 19, but those skilled in the art will appreciate that any convenient means for producing a point 21 may be employed in an extinguisher 10 of this invention. The tube member 19 is generally coaxial with conduit 12. The tube member 19 has a rear portion 24 which projects from the housing 1 1 and terminates in a discharge orifice 26. The rear portion of tube member 19 and the discharge orifice 26 may be of any desired shape or design, as those skilled in the art will appreciate.

The tube member 19 is adapted to reciprocally move along axis 17 between respective open and closed positions, the position shown generally in FIG. 1 being the open position, while that shown in FIG. 4 is the closed position. In the closed position, the point 21 is gener ally adjacent the mouth region 27a of the conduit 12. In the region where the tube member 19 passes through the housing 11, the sectors 11a and 11b of housing 11 are parted to provide a circumferential bearing surface 28 about the tube member 19 to permit such reciprocal movements thereof relative to the housing 11, thus the conduit 12 and the bearing surface 28 provide guide means for the tube member 19 during its reciprocal movements. The tube member 19, conduit 12, and V- shaped members 22 and 23 are conveniently formed of metals, such as steel, or the like.

Circumferentially about tube member 19 about midway between the inner end 25 of conduit 12 and the bearing surface 28 is mounted as by welding or the like a shoulder 29 formed of steel or the like. In the region between shoulder 29 and bearing surface 28 in housing 11 is circumferentially positioned about tube member 19 a tensioning spring member 31 which is adapted to provide a relatively strong spring bias relatively drivingly urging the plunger assembly 18 into its closed position.

A thermally responsive expansion tube 32 is utilized in extinguisher 10 to sense temperature changes. The tube 32 is conveniently formed of accordion-pleated brass or the like and is filled with a liquid or gas having a known expansion rate, as those skilled in the art will appreciate. In housing 11 the section 11a is conveniently formed or cast so as to provide an appropriate chamber 33 suitable for holding the tube 32.

The tube 32 is mounted in the housing 11 in spaced relationship to the plunger assembly 18 and the tube 32 is so arranged as to have a spatially fixable end 38 and a spatially elongatable end 39 adapted for predetermined elongation movement in a direction generally parallel to the axis 17.

In the preferred embodiment 10, a temperature adjusting screw 34 is threadably extended through the section 11a into a cylindrical section 37 adjacent to and coaxial with the chamber 33. The cylindrical section 37 serves as a guide for a temperature adjusting plate 38. The screw 34 is conveniently set after adjustment in a predetermined position by some means, such as nut 36 or the like. The temperature adjusting plate 38a abuts against end 38 of the tube 32. Thus, the tube 32 is provided with an adjustable travel limit stop which permits one to effectively adjust the longitudinal length of tube 32, and hence to vary the release temperature of extinguisher over a broad range, as those skilled in the art will appreciate. This adjustment permits one to utilize the fire extinguisher 10 for a number of different types of applications without major modification.

A lever 41 is provided which is adapted for pivotal movements about a fulcrum 42 whose pivot axis is generally perpendicular to axis 17. Fulcrum 42 is generally located adjacent the elongatable end 39 of tube 32. One arm 43 of lever 41 is adapted to engage elongatable end 39 while the other arm of lever 41 is adapted to engage the shoulder 29 of tube 19 and thereby to hold the plunger assembly 18 in a normally open position when the tube 32 is in a predetermined contracted configuration, such as typically exists at ambient temperature conditions. The lever 41 is adapted to release the tube member 19 ofa plunger assembly 18 from the normally open position whenever the tube 19 elongates and the elongatable end 39 causes the arm 43 to thus produce a pivotal movement in lever 41 about fulcrum 42, so that arm 41, after an initial slight raising action against shoulder 29, slips off the shoulder 29, thereby releasing the tube member 19 of plunger assembly 18. The spring 31 drives the tube member 19 into the closed configuration which results in driving the point 21 into and preferably through the mouth of the conduit 12.

Across the mouth of conduit 12 is mounted the orifice of a sealed cannister 46. Cannister 46 is one of the types adapted to hold a pressurized fire retardant material, such as carbon dioxide gas, a dry chemical of the bicarbonate type, or the like. Such cannisters and the flame retardant materials used therein are known in the art and do not form a part of this invention. One may employ a variety of different cannisters with a given thermally responsive release mechanism of this invention, as those skilled in the art will readily appreciate.

A cannister 46 typically has a neck region 47 across the mouth of which is normally mounted a normally sealed rupture plate 48. The neck region 47 is adapted to engage by some means the mouth of conduit 12. Thus, for example, in extinguisher 10, such engagement is accomplished by means of a threaded collar 49 integrally formed with conduit 12 which is adapted to engage the corresponding mating threads formed on the neck region 47 of a cannister 46, thereby permitting in a cannister 46 to readily attach to, and detach from, collar 49. The rupture plate 48 is penetrated by point 21 as tube member 19 is driven into its closed position, as shown in FIG. 4, when lever 41 releases the shoulder 29 as the tube 32 expands in response to an increase in temperature.

In extinguisher 10, as soon as a rupture plate 48 is broken, the flame retardant material within pressurized cannister 46 is discharged therefrom through the conduit 12, through the openings about the crossed V- shaped members 22 and 23, through the tube member 19, through rear portion 24 of tube 19, and finally out through the discharge orifice 26. Movement of flame retardant material from a cannister 46 through tube 19 is illustrated by the arrows shown in FIG. 4.

The shoulder 29 acts as a convenient stop limiting movement of tube member 19 by spring 31 as shoulder 29 is forced against the inside end of the conduit 12 as the spring 31 expands. Particularly in the case where the cannister 46 is filled with a gaseous flame retardant material, such as carbon dioxide or the like. it is convenient and preferred to provide sealing means between telescopically engaged sections of the conduit 12 and the tube member 19. Such sealing means in extinguisher 10 is conveniently provided by O-ring seals 51 and 52 which seat in appropriately formed circumferentially extending grooves formed on inside walls of the conduit 12.

Sections 11a and 1112 are conveniently mounted together by means of screws 16 which extend through appropriately thickened side wall portions of section 11); into threaded socket portions mating therewith formed in section 11a, through any convenient securing means for sections 11a and 1112 may be employed. It is preferred for equilization and air temperature sensing purposes to have the housing 11 equipped with orifices 53 which are adapted to permit air to move into and out of the housing 11, as those skilled in the art will readily appreciate.

To yieldingly bias relatively weakly arm 43 against elongatable end 39 a tensioning spring 54 is provided which is mounted at one end thereof to housing 11 adjacent chamber 33 and at the other end thereof to the end of the arm 43 as shown in FIG. 1.

Preferably, extinguisher 10 is additionally equipped with a release means adapted to permit actuation of plunger assembly 18 manually to move tube 19 from an open to a closed position. For example, in extinguisher 10, there is provided a shaft 56 which is journalled for axial reciprocal movements through a hole 55 in housing 11. At its rear end 58 a shaft 56 pivotally connects with the end of arm 43 through a tab 59 rigidly fixed to shaft 56 and a rivet device 61, or the like, pivotal movements of arm 44 relative to the tab 59 being permitted by rivet 61. Thus, by pressure manually applied to the bottom 57 on shaft 56, lever 41 is caused to pivot on its fulcrum 42 and to release the tube 19 at shoulder 29.

Preferably, extinguisher 10 is equipped with an interlock means to retain the plunger assembly 18 in an open position independently of the position of lever 41 or of the elongation of tube 32. For example, in extinguisher 10, a pin 62 formed of steel, or the like, is extended transversely through appropriate aligned apertures 63 formed in housing 11 adjacent to the shoulder 29 and beyond spring 31. With the plunger assembly 18 in its normally open configuration, the pin 62 is conveniently manually inserted into or removed from, the housing 11. Pin 62 provides a desirable safety device for preventing premature activation of plunger assembly 18 during storage, shipping, or the like, of extinguisher 10.

Those skilled in the art will appreciate that, within the spirit and scope of the present'invention, many different mounting configurations for a tube 32 within a housing 11 are possible. Thus, referring to FIG. 5, there is seen a portion of an alternative embodiment of a fire extinguisher of this invention, herein designed in its entirety by the numeral 66. Extinguisher 66 utilizes a housing 67 within which is conveniently mounted a plunger assembly which may be similar to that incorporated into extinguisher (not shown). Extinguisher 66 utilizes an expansion tube means 68 of the type similar to that employed in extinguisher 10. In extinguisher 66, tube means 68 is, in effect, circumferentially surrounded by three sides of housing 67, and a plurality of apertures in the housing 67 are adjacent tube means 68, thus permitting the tube means 68 to be quite responsive to relatively minor changes in ambient environmental temperatures in the region of the fire extinguisher 66. A lever 69 is pivoted by elongation movements of the tube 68 to releasethe plunger assembly (not shown). A manual override release lever mechanism 71 is provided to permit the lever 60 to be pivoted independently of the tube 68.

An extinguisher 10 or 66 is preferably designed to re lease substantially completely all the flame retardant material in a cannister after combustion temperatures are reached, or after a set temperature is reached, in the vicinity of such. Those skilled in the art will appre ciate that one may employ in combustion with thermal expansion tabs 32 or 68a supplemental capillary tube thermocouple. The tube 19 and also the tube 12 in extinguisher 10 are preferably formed of a metal such as chromed brass to make such less affected by corrosives, oxidation, and'the like.

Other and further embodiments, modifications and the like of the present invention will be apparent to those skilled in the art from a reading of the present specification and drawings, and no undue limitations are to be drawn therefrom.

1 claim:

1. A heat activated, self-discharging fire exinguisher comprising:

A. a housing,

B. conduit means associated with said housing and having a forward end and a rear end, and including an initial section extending back from said forward end thereof, said initial section having a generally straight axis,

C. plunger means having a forward portion terminating in a point, said plunger means being adapted for reciprocal movements along said axis between respective open and closed positions, said forward portion extending into said initial section so that said point is adjacent said forward end in said closed position, said plunger means including guide means associated with said housing, and shoulder means laterally projecting therefrom longitudinally behind said forward portion,

D. said conduit means and said plunger means cooperating to provide when said plunger means is in said closed position a passageway extending from said forward end to a discharge end outside said housing,

E. spring bias means drivingly urging said plunger means into said closed position,

thermally responsive expansion tube means adapted to elongate in response to increasing temperatures in the environment thereof and associated with said housing in spaced relationship to said plunger means, said tube means having a spatially fixable end and a spatially elongatable end adapted for predetermined elongation movement from a contracted configuration in a direction generally parallel to said axis,

G. lever means adapted for pivotal movements about a fulcrum whose pivot axis is generally perpendicular to said axis, said fulcrum being generally located adjacent said elongatable end, one arm of said lever means being adapted to engage said elongatable end, the other arm of said lever means being adapted to engage said shoulder and hold said plunger means in said open position when said tube means is in a contracted configuration, said lever means being further adapted to release said plunger means from said open position when said tube means elongates,

H. cannister means adapted to hold pressurized fire retardant material and having a neck region wherein is fixed a normally sealed rupture plate means,

I. engaging means interconnecting said neck region with said forward end and positioning said diaphragm means for penetration by said point when said plunger means is so released whereby said fire retardant material is dischargeable from said cannister through said conduit means and out said discharge end, and

J. yielding means biasing relatively weakly said one arm against said elongatable end.

2. A heat activated, self-discharging fire extinguisher comprising:

A. a housing,

B. conduit means associated with said housing and having a forward end and a rear end, and including an initial section extending back from said forward end thereof, said initial section having a generally straight axis, said conduit means terminating in said housing.

C. an elongated, hollow plunger means having a forward portion terminating in a point, said forward portion having apertures defined therein adjacent said point thereof, said plunger means being adapted for telescopic reciprocal movements coaxially in said conduit means along said axis between respective open and closed positions, said forward portion extending into said initial section so that said point is adjacent said forward end in said closed position, said plunger means further having a rear portion projecting from said housing and terminating in a discharge orifice, said plunger means including guide means associated with said housing, and shoulder means laterally projecting therefrom longitudinally behind said forward portion,

D. said conduit means and said plunger means cooperating to provide when said plunger means is in said closed position a passageway extending from said'forward end to said discharge orifice, said passageway being adapted for conveying therethrough said fire retardant material,

E. spring bias means drivingly urging said plunger means into said closed position,

thermally responsive expansion tube means adapted to elongate in response to increasing temperatures in the environment thereof and associated with said housing in spaced relationship to said plunger means, said tube means having a spatially fixable end and a spatially elongatable end adapted for predetermined elongation movement from a contracted configuration in a direction generally parallel to said axis,

G. lever means adapted for pivotal movements about a fulcrum whose pivot axis is generally perpendicular to said axis, said fulcrum being generally located adjacent said elongatable end, one arm of said lever means being adapted to engage said elongatable end, the other arm of said lever means being adapted to engage said shoulder and hold said plunger means in said open position when said tube means is in a contracted configuration, said lever means being further adapted to release said plunger means from said open position when said tube means elongates,

H. cannister means adapted to hold pressurized fire retardant material and having a neck region wherein is fixed a normally sealed rupture plate means, and

l. engaging means interconnecting said neck region with said forward end and positioning said diaphragm means for penetration by said point when said plunger means is so released whereby said fire retardant material is dischargeable from said cannister through said conduit means and out said discharge end.

3. The fire extinguisher of claim 2 further including adjustment means for varying the position of said spatially fixable end.

4. The fire extinguisher of claim 2 additionally equipped with lever release means adapted to permit release of said plunger means by said lever means independently of said expansion tube means.

5. The fire extinguisher of claim 2 additionally equipped with interlock means for said plunger means adapted to retain said plunger means in said open position independently of said lever means.

6. A thermally responsive release mechanism adapted for mounting with a pressurized rupture plate equipped cannister of fire retardant material comprising:

A. a housing,

B. conduit means associated with said housing and having a forward end and a rear end, and including an initial section extending back from said forward end thereof, said initial section having a generally straight axis, said forward end being adaptable for interconnection with a prechosen said cannister adjacent the rupture plate thereof,

C. plunger means having a forward portion terminating in a point, said plunger means being adapted for reciprocal movements along said axis between respective open and closed positions, said forward portion extending into said initial section so that said point is adjacent said forward end in said closed position, said plunger means including guide means associated with said housing, and shoulder means laterally projecting therefrom longitudinally behind said forward portion,

D. said conduit means and said plunger means cooperating to provide when said plunger means is in said closed position a passageway extending from said forward end to a discharge end outside said housing.

E. spring bias means drivingly urging said plunger means into said closed position,

thermally responsive expansion tube means adapted to elongate in response to increasing temperatures in the environment thereof and associated with said housing in spaced relationship to said plunger means, said tube means having a spa tially fixable end and a spatially elongatable end adapted for predetermined elongation movement from a contracted configuration in a direction generally parallel to said axis,

G. lever means adapted for pivotal movements about a fulcrum whose pivot axis is generally perpendicular to said axis, said fulcrum being generally located adjacent said elongatable end, one arm of said lever means being adapted to engage said clongatable end, the other arm of said lever means being adapted to engage said shoulder and hold said plunger means in said open position when said tube means is in a contracted configuration, said lever means being further adapted to release said plunger means from said open position when said tube means elongates, and

H. adjustment means for varying the position of said spatially fixable end.

7. The mechanism of claim 6 further including yielding means biasing relatively weakly said one arm against said elongatable end.

8. The mechanism of claim 6 wherein:

A. said plunger means is elongated and generally hollow and said forward portion has apertures defined therein adjacent said point thereof,

B. said plunger means generally telescopically reciprocates coaxially in said conduit means and said conduit means terminates in said housing,

C. said plunger means has a rear portion projecting from said housing and terminating in a discharge orifice, and

D. said plunger means and said conduit means in combination define a passageway through said housing adapted for conveying therethrough said fire retardant material.

9. The mechanism of claim 6 additionally equipped with lever release means adapted to permit release of said plunger means by said lever means independently of said expansion tube means.

10. The mechanism of claim 6 additionally equipped with interlock means for said plunger means adapted to retain said plunger means in said open position independently of said lever means. 

1. A heat activated, self-discharging fire exinguisher comprising: A. a housing, B. conduit means associated with said housing and having a forward end and a rear end, and including an initial section extending back from said forward end thereof, said initial section having a generally straight axis, C. plunger means having a forward portion terminating in a point, said plunger means being adapted for reciprocal movements along said axis between respective open and closed positions, said forward portion extending into said initial section so that said point is adjacent said forward end in said closed position, said plunger means including guide means associated with said housing, and shoulder means laterally projecting therefrom longitudinally behind said forward portion, D. said conduit means and said plunger means cooperating to provide when said plunger means is in said closed position a passageway extending from said forward end to a discharge end outside said housing, E. spring bias means drivingly urging said plunger means into said closed position, F. thermally responsive expansion tube means adapted to elongate in response to increasing temperatures in the environment thereof and associated with said housing in spaced relationship to said plunger means, said tube means having a spatially fixable end and a spatially elongatable end adapted for predetermined elongation movement from a contracted configuration in a direction generally parallel to said axis, G. lever means adapted for pivotal movements about a fulcrum whose pivot axis is generally perpendicular to said axis, said fulcrum being generally located adjacent said elongatable end, one arm of said lever means being adapted to engage said elongatable end, the other arm of said lever means being adapted to engage said shoulder and hold said plunger means in said open position when said tube means is in a contracted configuration, said lever means being further adapted to release said plunger means from said open position when said tube means elongates, H. cannister means adapted to hold pressurized fire retardant material and having a neck region wherein is fixed a normally sealed rupture plate means, I. engaging means interconnecting said neck region with said forward end and positioning said diaphragm means for penetration by said point when said plunger means is so released whereby said fire retardant material is dischargeable from said cannister through said conduit means and out said discharge end, and J. yielding means biasing relatively weakly said one arm against said elongatable end.
 2. A heat activated, self-discharging fire extinguisher comprising: A. a housing, B. conduit means associated with said housing and having a forward end and a rear end, and including an initial section extending back from said forward end thereof, said initial section having a generally straight axis, said conduit means terminating in said housing. C. an elongated, hollow plunger means having a forward portion terminating in a point, said forward portion having apertures defined therein adjacent said point thereof, said plunger means being adapted for telescopic reciprocal movements coaxially in said conduit means along said axis between respective open and closed positions, said forward portion extending into said initial section so that said point is adjacent said forward end in said closed position, said plunger means further having a rear portion projecting from said housing and terminating in a discharge orifice, said plunger means including guide means associated with said housing, and shoulder means laterally projecting therefrom longitudinally behind said forward portion, D. said conduit means and said plunger means cooperating to proVide when said plunger means is in said closed position a passageway extending from said forward end to said discharge orifice, said passageway being adapted for conveying therethrough said fire retardant material, E. spring bias means drivingly urging said plunger means into said closed position, F. thermally responsive expansion tube means adapted to elongate in response to increasing temperatures in the environment thereof and associated with said housing in spaced relationship to said plunger means, said tube means having a spatially fixable end and a spatially elongatable end adapted for predetermined elongation movement from a contracted configuration in a direction generally parallel to said axis, G. lever means adapted for pivotal movements about a fulcrum whose pivot axis is generally perpendicular to said axis, said fulcrum being generally located adjacent said elongatable end, one arm of said lever means being adapted to engage said elongatable end, the other arm of said lever means being adapted to engage said shoulder and hold said plunger means in said open position when said tube means is in a contracted configuration, said lever means being further adapted to release said plunger means from said open position when said tube means elongates, H. cannister means adapted to hold pressurized fire retardant material and having a neck region wherein is fixed a normally sealed rupture plate means, and I. engaging means interconnecting said neck region with said forward end and positioning said diaphragm means for penetration by said point when said plunger means is so released whereby said fire retardant material is dischargeable from said cannister through said conduit means and out said discharge end.
 3. The fire extinguisher of claim 2 further including adjustment means for varying the position of said spatially fixable end.
 4. The fire extinguisher of claim 2 additionally equipped with lever release means adapted to permit release of said plunger means by said lever means independently of said expansion tube means.
 5. The fire extinguisher of claim 2 additionally equipped with interlock means for said plunger means adapted to retain said plunger means in said open position independently of said lever means.
 6. A thermally responsive release mechanism adapted for mounting with a pressurized rupture plate equipped cannister of fire retardant material comprising: A. a housing, B. conduit means associated with said housing and having a forward end and a rear end, and including an initial section extending back from said forward end thereof, said initial section having a generally straight axis, said forward end being adaptable for interconnection with a prechosen said cannister adjacent the rupture plate thereof, C. plunger means having a forward portion terminating in a point, said plunger means being adapted for reciprocal movements along said axis between respective open and closed positions, said forward portion extending into said initial section so that said point is adjacent said forward end in said closed position, said plunger means including guide means associated with said housing, and shoulder means laterally projecting therefrom longitudinally behind said forward portion, D. said conduit means and said plunger means cooperating to provide when said plunger means is in said closed position a passageway extending from said forward end to a discharge end outside said housing, E. spring bias means drivingly urging said plunger means into said closed position, F. thermally responsive expansion tube means adapted to elongate in response to increasing temperatures in the environment thereof and associated with said housing in spaced relationship to said plunger means, said tube means having a spatially fixable end and a spatially elongatable end adapted for predetermined elongation movement from a contracted configuration in a direction generally parallel to said axiS, G. lever means adapted for pivotal movements about a fulcrum whose pivot axis is generally perpendicular to said axis, said fulcrum being generally located adjacent said elongatable end, one arm of said lever means being adapted to engage said elongatable end, the other arm of said lever means being adapted to engage said shoulder and hold said plunger means in said open position when said tube means is in a contracted configuration, said lever means being further adapted to release said plunger means from said open position when said tube means elongates, and H. adjustment means for varying the position of said spatially fixable end.
 7. The mechanism of claim 6 further including yielding means biasing relatively weakly said one arm against said elongatable end.
 8. The mechanism of claim 6 wherein: A. said plunger means is elongated and generally hollow and said forward portion has apertures defined therein adjacent said point thereof, B. said plunger means generally telescopically reciprocates coaxially in said conduit means and said conduit means terminates in said housing, C. said plunger means has a rear portion projecting from said housing and terminating in a discharge orifice, and D. said plunger means and said conduit means in combination define a passageway through said housing adapted for conveying therethrough said fire retardant material.
 9. The mechanism of claim 6 additionally equipped with lever release means adapted to permit release of said plunger means by said lever means independently of said expansion tube means.
 10. The mechanism of claim 6 additionally equipped with interlock means for said plunger means adapted to retain said plunger means in said open position independently of said lever means. 